// 1.将A5F3转成2进制
    var c ='A5F3';
    var d = parseInt(c,16)
    console.log(d.toString(2));
// 2.99乘法表
    var a=1;
    
    while (a<10) {
        var b=1;
        while (b<=a) {
           document.write(b,'*',a,'=',a*b,'&nbsp;') 
           b++;
        }
        document.write('<br>')
        a++;
    }
// 3.输入年月，（用数组）
    var date =prompt('输入日期，用.分割')  ;
    const arr = date.split('.'); 
    var year= arr[0];
    var month= arr[1];
    var day= arr[2];
//       3.1.计算当月有多少天
        if (month==2) {
            if (year%4==0&&year%100!=0) {
                console.log(month,'月有',29,'天');
            }else{
                console.log(month,'月有',28,'天');
            }
        }else if (month==1||month==3||month==5||month==7||month==8||month==10||month==12) {
            console.log(month,'月有',31,'天');
        }else if (month==4||month==6||month==9||month==11) {
            console.log(month,'月有',30,'天');
        } 
//       3.2.计算还剩多少天
    if (month==2) {
        if (year%4==0&&year%100!=0) {
            console.log(month,'月还有',29-day,'天');
        }else{
            console.log(month,'月还有',28-day,'天');
        }
    }else if (month==1||month==3||month==5||month==7||month==8||month==10||month==12) {
        console.log(month,'月还有',31-day,'天');
    }else if (month==4||month==6||month==9||month==11) {
        console.log(month,'月还有',30-day,'天');
    }
